Pressure compensating IV flow control regulator

ABSTRACT

A pressure compensating IV rate flow regulator having a housing with a metering port and an outlet. The flow rate is set by adjusting a flexible disk to vary the clearance between a metering port and flow passageway. The controlled fluid passes to a land surrounding the outlet. A flexible control membrane having specific design and material characteristics extends across the land and will move or oscillate away or towards the outlet port in response to changes in head pressure, venous back pressure or patient movement. The resulting oscillation of the membrane serves to maintain the flow rate originally set by the clinician. The regulator is provided with safety and operational convenience features such as tactile indicators for “off” and KVO settings and has provision for use with accessory items such as a pole mount holder or anchoring device secured at the forearm or chest.

CROSS REFERENCE TO PREVIOUS APPLICATION

[0001] This application is based on provisional patent application S No.60/349,834, filed Jan. 16, 2002, entitled “Pressure Compensated FlowRegulator.”

FIELD OF THE INVENTION

[0002] The present invention relates to a device for regulating andcontrolling the flow of intravenous solutions to a patient in a gravityinfusion system. More particularly, the present invention relates to adisposable, single-use, gravity-flow regulator which is adjustable toclosely maintain a pre-set flow rate independent of pressure change dueto changes in elevation of the fluid container, venous backpressure orpatient movement.

BACKGROUND OF THE INVENTION

[0003] Gravity administration of fluids by IV infusion, also known as IVtherapy, is a widely practiced medical procedure. Drugs and fluids suchas blood, plasma, dextrose and isotonic saline solutions areadministered to patients in this manner.

[0004] In the typical administration set, a container containing the IVsolution is provided to the attending medical personnel. The containerhas a seal which is broken by insertion of a piercing spike on the dripchamber. A flexible tubing line delivers the IV fluid to the patient.The purpose of the drop chamber is to facilitate the determination offlow or drip rate through the tubing. Infusion rates may be regulated bythe use of an external pinch valve or roller clamp associated with thetubing for less critical gravity-type infusions.

[0005] The procedure involves initially purging the tubing and needle ofair by initiating a flow of fluid through the tubing. Once this is done,the needle is then inserted into the venipuncture site, such as alocation in the forearm or wrist of the patient, and fluid flow isinitiated. Medical personnel will normally adjust a pinch valve orroller clamp to restrict the IV tubing. The number of drops passingthrough the drip chamber is visually counted or timed. The appropriateflow rate is established by trial and error by progressively restrictingor opening the lumen in the tubing using the pinch valve or rollerclamp. Roller clamps and pinch valves compress the delivery tubing andare not very accurate as they deform the tubing due to the physicalproperties of the tubing, the inner diameter may change during use.

[0006] The administration procedure described above requires theattention of medical personnel for a substantial period of time.However, once a drop rate is set, the rate can be subject to substantialdeviation as a result of a number of factors. As the administration ofthe IV progresses, the fluid level within the solution container willlower, reducing the effective head pressure, causing the drop rate toreduce. The drop rate may also be significantly affected by a change inthe elevation of the container or by movement of the patient.Accordingly, the traditional clamping procedures are subject to errorand deviation and may deliver fluid at too low or too high a rate whichmay be adverse to the patient, particularly critical care patients.

[0007] Accordingly, various approaches can be found in the prior art tomaintaining constant IV flow rates in gravity systems. Flow can beregulated by controlling pressure or resistence either mechanically orelectro-mechanically. For example, U.S. Pat. No. 4,343,5305, disclosesan adjustable rate, constant output infusion set having a connectorpiece connectable to a container and a headpiece rotatably attached tothe connector to adjust the flow rate. An elastically stretchablediaphragm is interposed between the connector piece and the head piece.The connector piece forms a first chamber with a diaphragm which is indirect communication with the container by an inlet port. The headpieceforms a second chamber with a diaphragm, which is in communication withthe patient by a control board. The headpiece is rotatably attached tothe connector to adjust the flow rate. A passageway connects the firstchamber and the second chamber and the diaphragm and by virtue ofelasticity maintains a constant pressure drop between the chambers sothat the fluid passes the control port at a constant rate of flow.

[0008] U.S. Pat. No. 4,515,588 shows a flow regulator for use in an IVadministration arrangement which establishes and maintains the rate offlow regardless of changes of head. The regulator utilizes a diaphragmcontrol orifice and bypass with a valve to establish the flow rate. Thediaphragm adjusts the effective orifice opening to maintain the constantflow selected by the valve setting.

[0009] U.S. Pat. No. 4,769,012 discloses a flow regulating device forgravity infusion and transfusion of fluids which has an upper and lowerhousing and having inlet and outlet channels respectively. Acontinuously adjustable valve is connected between the inflow andoutflow channels. The outflow channel has an outlet opening whichdefines a valve seat and a membrane extends across the outlet openingand is movable toward and away from the outlet opening, depending onpressure occurring on opposite sides of the membrane. In this way,extraneous factors such as patient venous pressure can be compensated bythe membrane to maintain substantially constant flow of fluid once thevalve is set.

[0010] U.S. Pat. No. 5,240,035 discloses a pressure compensator formaintaining essentially constant flow rates in an IV system having asource of IV fluid and a controller. The compensator is connectable tothe controller and has a housing with a flexible membrane extendingtransversely therein defining opposite control chambers. One controlchamber communicates with the source of IV fluid and also connects tothe inlet of the flow controller. The second control chamber receivesthe regulated flow from the control valve. The second control chamber isgenerally conical or convex, sloping to an outlet port which isconnected to the tubing line leading to the patient. The outlet from thesecond chamber is smaller than the inlet to the second chamber and thediaphragm serves to control flow to the patient by compensating forpressure changes, such as change in fluid head. The configuration of thesecond chamber and the configuration of the outlet in the second chamberminimize air entrapment and provide greater flow capacity.

[0011] While devices of the type described above improve accuracy in IVdelivery systems, there nevertheless exists a need for a cost-effective,reliable, accurate and effective IV regulator which will maintain asubstantially constant flow of IV fluid once a flow rate is set. Therefurther exists a need for a device which requires minimal manipulationso that when the regulator is placed in use in an IV administrationsystem, the requirement for drop counting and readjustment is eitherminimized or eliminated.

BRIEF SUMMARY OF THE INVENTION

[0012] Briefly, the present invention provides a gravity flow rateregulator for administering IV solutions. The regulator is connectableto a line leading to the IV fluid container at a tubing connector. Thesolution container is supported in a position above the venipuncturesite so that fluid will flow by means of gravity through the tubing tothe venipuncture site. The regulator is adapted to be interposed in thetubing line between the IV solution container and patient.

[0013] The regulator has a housing which supports a flexible membraneinterposed between an inlet and outlet, establishing inlet and outletchambers. Fluid from the IV container enters the housing through aninlet port which, in one embodiment, is disposed at an angle withrespect to the regulator body. As the fluid flows through the regulatorto the outlet it passes across a metering port and into an outletchamber surrounding the outlet. The outlet chamber has a raised landsurrounding an orifice opening into the outlet. A flexible membrane isdisposed across the land so that flexing or oscillating of the membranetoward or away from the orifice will control the flow of liquid throughthe outlet orifice. The membrane is subject to outlet pressure againstits lower surface and to inlet or head pressure against its oppositeupper surface. The pressure differential across the membrane operates tomaintain the preset flow through the outlet by oscillating to adjust theeffective opening of the orifice to compensate for changes in fluidpressure.

[0014] A valving device such as a screw attached to a large control dialprovides precise control so the medical attendant may easily andaccurately establish the rate of flow through the metering port byprogressively advancing or retracting an elastomeric disk with respectto a flow passage in the fluid flow path in the regulator.

[0015] The control dial for manually setting the flow rate is providedwith a detent that provides a tactile indication of settings such as KVO(keep vein open), an “off” or locking position as well as providing astop at the full flow position. The dial is further provided with asafety lock to prevent inadvertent or unauthorized changing of the dialsetting once it is set. The dial has spaced grooves extending around thedial engaging a fixed projection so that the user is provided tactilefeedback as the dial is manually rotated between settings.

[0016] The regulator membrane and metering disk are selected havingspecific characteristics to ensure accuracy. Other features of theregulator include internal sealing to minimize leakage and a largeradius outlet port for debubbling. In an alternate embodiment, the inletport extends through an arcuate slot in the dial so a large, manuallyadjustable dial may be utilized. The regulator may be used with varioustypes of IV fluids, even high viscosity fluids and lipids.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects and advantages of the presentinvention will become more apparent from the following descriptions,claims and drawings in which:

[0018]FIG. 1 is a schematic view of a representative IV administrationsystem incorporating the flow control regulator of the presentinvention;

[0019]FIG. 2 is a bottom exploded view of the flow regulator of thepresent invention;

[0020]FIG. 3 is a top exploded view of the flow regulator of the presentinvention;

[0021]FIG. 4 is a perspective view of the screw housing;

[0022]FIG. 5 is an exploded vertical cross-sectional view of theregulator;

[0023]FIG. 6 is an enlarged cross-sectional view of the regulator;

[0024]FIG. 7 is a perspective view of the dial showing detent whichprovides a tactile indication and retention of the “off” position;

[0025]FIG. 8 shows the dial safety lock position preventing inadvertentpositioning of the dial;

[0026]FIG. 9 is a schematic diagram illustrating the flow path throughthe regulator;

[0027]FIG. 10 is a perspective view illustrating another configurationof the regulator body;

[0028]FIG. 11 shows the regulator attached to an accessory pole mountholder by an anchoring or securement device;

[0029]FIG. 11A shows the regulator of the invention attached to asecurement device, the securement device being securable to the chest orforearm of the patient; and

[0030]FIG. 12 shows the top surface of the dial.

DETAILED DESCRIPTION OF THE DRAWINGS

[0031] Turning now to the drawings, particularly FIGS. 1 to 9, anembodiment of the pressure compensated flow control regulator of thepresent invention is shown and generally designated by the numeral 10.The flow control regulator 10 is a gravity-flow regulator and preferablyis a disposable, single-use device provided to the user in a sterilizedpackage. Gravity devices rely on fluid head pressure to overcome theback pressure of the patient's venous system. As seen in FIG. 1, in usethe regulator 10 is interposed at a location between an IV fluid source12 and the patient P. The flow regulator is connected to tubing line 16which leads to an IV drip chamber 15 inserted into an IV fluid source 12at a piercing spike. It is customary to locate the flow controlregulator at an intermediate elevation below the level of the IV fluid.

[0032] The outlet of the flow control regulator 10 is connected toflexible tubing line 18 which leads to the patient and terminates at anadministration needle at the venipuncture site “V.” As discussed above,one problem with non-compensated flow control devices is that changes inhead pressure due to changes in the fluid level within the IV container,changes in elevation of the fluid container on the IV stand or movementof the patient's limb can adversely affect flow control rates. The majordetermination of pressure in gravity administration systems is headheight which refers to the distance between the fluid level in the IVsolution container and the IV site “V.”

[0033] In conventional systems, a roller clamp may be interposed betweenthe IV source and the regulator. In such systems, the roller clamp isused to establish a drop rate by counting drops. However, with theregulator of the present invention, use of a roller clamp is notnecessary for adjustment and may be incorporated for use only wheninitiating or stopping flow.

[0034] The flow control regulator 10 has a housing or body 24 consistingof components including an upper housing 36, an intermediate or middlehousing 28 and lower housing 31. These housing components are preferablyfabricated by injection molding using a suitable medical grade plasticmaterial such as ABS or polypropylene. Although the housing componentsare shown as separate components for ease of fabrication and assembly,they may be unitary.

[0035] Housing 28 has an inlet port 32 which defines an inlet passage29. The inlet port 32 is generally cylindrical and is sized to beconnectable to conventional medical tubing 16. The inlet port 32 ispreferably disposed at an angle greater than 45° with respect to thevertical axis of the regulator and may extend to 90°. The angularorientation of the inlet port 32 provides significant functionaladvantages in that the angular orientation facilitates use of aneasy-to-adjust dial 140 having a large diameter. The angular orientationof the inlet port also allows the regulator to hang in a suspended,in-line position with the surface of dial 140 in a vertical or nearvertical, easy-to-read position, as seen in FIG. 1.

[0036]FIG. 10 shows the regulator 10 with a large circular dial 140Awhich operates as has been described. To accommodate the large diameterdial 140A, the surface 141A is provided with an arcuate groove 143. Thisallows the inlet 32A to extend axially through the slot 143.

[0037] Circular wall surface 34 is provided with a concentric,downwardly depending circular flange 40 which engages the lower housing31. An annular flange 46 extends upwardly from the upper surface 34 at alocation offset from its center. At the center of the top surface areadefined by the upper flange 46 is a vertically extending orifice 50which has a generously radiused upper edge 51 which transitions to thetop surface of the wall. A small annular sealing ridge 52 on the uppersurface of wall 34 extends adjacent the flange 46.

[0038] A second orifice 43 is provided in wall surface 34 at the lowerend of the inlet passage 29. A shallow groove 56 extending in the bottomof wall 34 communicates orifice 43 with the center orifice 50. A radialflow passageway 58 along the top of wall 34 extends between the centerorifice 50 and orifice 54. Orifice 54 extends through wall 34 radiallyspaced from center orifice 50. These passageways are best seen in FIGS.2 and 3.

[0039] The lower housing 31 has a generally circular planar bottomsurface 60 with an upstanding peripheral flange 62 which, in theassembled position, engages the depending flange 40 of the middlehousing. An outlet fitting 64 depends at a central location from theoutlet housing. The fitting 64 is sized to accommodate attachment ofconventional medical tubing 18 which leads to the patient. The outletfitting 64 is spaced or offset from the location of orifice 54 locatedin the middle housing.

[0040] The upper surface of the lower housing wall defines a radiallyextending passageway 66 which, when the components are assembled, isaligned with orifice 54. An outlet orifice 70 extends through the bottomwall and is centered within an annular flange 74. The orifice is locatedin a raised, circular land 76 which surrounds the outlet orifice 70.

[0041] The peripheral outer edges of the upper housing and the lowerhousing define a peripheral groove 41 about the regulator body. Thegroove 41 accommodates temporary attachment of the regulator 10 to anaccessory such as a pole mount holder or a patient anchoring device suchas safety securement device, as seen in FIGS. 11 and 11A. The device 10is securable to a support pole S by securement device 200 and havingarms engageable in groove 41. The regulator may be easily “snapped” inplace with the arms of the holder engaging the groove 41. The securementdevice has a clamp 210 adjustably attachable to the pole S. In FIG. 11A,the regulator 10 is shown with a patient securement device 250 which hasa base 252 adhesively securable to the patient. The base 252 has aplurality of projections 256, 257 which releasibly engage the body ofthe regulator along peripheral groove 41.

[0042] An elastomeric membrane 80 is seated within chamber 82 defined bythe upper surface of the lower housing and with the lower surface of themiddle housing. The elastomeric membrane 80 is of a suitable medicalgrade material such as silicone rubber. The membrane has characteristicscritical to the performance of the regulator and the maintenance ofaccurate flow rates once set by the clinician. The membrane flexes oroscillates to regulate flow to compensate for pressure changes asdescribed above. The elastomeric membrane has a generally annular outerflange 84. A thin, flexible center section 86 extends across the inneredges of the annular section. Typically, the thin, flexible centersection of the membrane will have a thickness within the range of0.0125″ to 0.0175.″ The membrane is best seen in FIG. 3.

[0043] It has been found that a thinner membrane will generally providegreater accuracy at lower head height and less accuracy as head heightincreases. It has been found that an optimal thickness for the flexiblesection of the membrane is about 0.015″.

[0044] In the assembled position, the central membrane flexible section86 extends across top of land 76 and across outlet orifice 70. Smallannular sealing projections or ridges 88, 89 extend from the surfaces ofthe lower housing and upper housings positioned to sealingly engage theopposite surface of membrane flange 84 to prevent fluid leakage aroundthe edges of the membrane. The characteristics of the membrane 80 arecritical to proper operation. A membrane fabricated in accordance withthe following has been found to work well providing the necessarycontrol and accuracy.

[0045] The membrane is preferably fabricated by compression moldingusing a silicone material having the following characteristics listedbelow: MEMBRANE MATERIAL CHARACTERISTICS Durometer, Shore A  50 andabove ASTM D2240 Tensile Strength 1100 to 1200 ASTM D-412 Elongation % 200 to 300 ASTM D-412 Modulus @ 100%  60 to 70 ASTM D-624 Tear Strength 50 to 60 ASTM D-624 Bayshore  60 and above ASTM D-624

[0046] A vertical port 90 is provided in the annular portion 84 of themembrane and, when the regulator is assembled, aligns with the orifice54 in the inlet housing and communicates this passageway with theradially extending groove 66 in the upper surface of the bottom housing.Thus, as seen in FIG. 9, a flow path is established from the inletpassageway 29 through the orifice 43 at the bottom of the inlet passageand extending radially along channel 56 to central orifice 50 in themiddle housing. The flow path continues upwardly through orifice 50 andthen radially along channel 58 to a location registering with thevertical port 90 in the annular portion of the membrane 80. Fluid willthen flow downwardly through the port 90 to the radial passage 66 in thelower housing. Fluid will then pass between the membrane and the bottomsurface to an annular outlet chamber 95. This chamber 95 is defined byannular ring 74. Raised land 76 is located in the center of ring 74 anddefines an outlet orifice 70 communicating with the lumen in the outletfitting 64.

[0047] The flow control regulator further includes an upper housing 36.The upper housing 36 has a generally cylindrical body 100 which, whenassembled, is received within the annular flange 46 of the middlehousing 28. The upper housing 36 defines a vertical bore 104 which isaligned with an orifice in the middle housing. Bore 104 defines theplurality of screw threads 106 which are preferably left hand threads.An elastomeric flow control disk 120 is seated on the upper surface ofthe middle housing extending across the upper end of the orifice 50. Anadjusting screw 110 is threadably received in the threaded bore 104. Theadjusting screw has a body with external male threads 130 which areengageable with the threads 106 in the upper housing.

[0048] The pitch of the mating screw threads 106 and 130 are selected toprovide ease of adjustment and to spread the range of adjustment overabout 360° of dial rotation. A thread pitch of about 48 has been foundto work well providing medical technicians “feel” for the preciseadjustment. The lower end of the screw body tapers to a rounded point132 which engages the upper surface of the elastomeric disk 120.

[0049] The disk 120 is preferably molded silicon having a thicknessapproximately 0.070″. The preferred material characteristics for thecontrol disk are set forth in the above Material Characteristic chartbelow. CONTROL DISK MATERIAL CHARACTERISTICS Test Method DescriptionUnit Lower Unit Upper Unit COMPRESSION SET 22/350F % 0 35 A/B BLEND PBDUROMETER A/B BLEND PB No Unit 57 65 ELONGATION A/B BLEND PB % 320 550MODULUS 100% PSI A/B psi 0 900 BLEND PB TENSILE PSI A/B BLEND PB psi1159 2000 TEAR B PPI A/B BLEND PB ppi 143 400 SPECIFIC GRAVITY No Unit1.11 1.15 DENSITRON ASTM792-A GOETTFERT T90 MINUTES min 4.5 6.5GOETTFERT RHEOMETER ° C. 113.0 120.0 C.I.T. LINEAR PRG.

[0050] The upper end of the screw 110 has a plurality of axial ribs 134which are received within the cooperating opening 138 in the controldial 140. The control dial 140 has an upper generally planar surface 141which has a substantial diameter for ease of use and which may beprovided with flow rate indicia graduations 180 from 0 to full flowwhich are positioned relative to the screw when the regulator iscalibrated, as seen in FIG. 12. The graduations are indexed withreference to indicator 146 located on the inlet 32 as best seen in FIG.12. The outer edge of the control dial forms a downwardly dependingsurface 142 which may be ribbed or knurled on its exterior for ease ofuse. An inner, annular flange 144 closely cooperates with the smooth,outer surface 105 of the housing 36 having cooperating grooves 148 sothe dial may be “snapped” in place over the upper end of the screw andsecured to the screw in a desired calibration position at assembly withrespect to the upper housing and disk 120.

[0051] It will be apparent that by rotating the control dial, rotationwill also be imparted to the adjusting screw 110. As the adjusting screwis advanced by rotating the dial in a counterclockwise direction, theelastomeric disk 120 will be forced downwardly toward the upper radiusededge 51 of the control orifice 50 reducing the clearance between theorifice 50 and passageway 59 to reduce the flow rate. Rotation of thecontrol dial in the opposite direction will open the clearance at thecontrol orifice permitting greater flow rate. The upper housing 36carries flow rate indicia 180 which cooperates with indicator 146 alongthe center portion of the inlet port 32. The graduations 180 on theupper surface 141 of the control dial indicate flow regulatingpositions, full off, full flow and purge positions and with intermediateflow rate or graduations indicated between these positions. The flowcontrol regulator is calibrated at the time of assembly as will beexplained hereafter.

[0052] Referring to FIGS. 4, 7 and 8, several safety features are shown.The control dial 140 may be rotated approximately 360° from “off” to afull open or purge position. In order to provide a positive indicationof the “off” position so that a low rate of fluid flow is notinadvertently delivered to the patient, the dial is provided with adetent feature. As seen in FIGS. 4 and 7, a circular flange 155 on theunderside of the dial is provided with two adjacent projecting ridges150, 152 connected by a land area 154. Ridge 150 is shallower than ridge152. A stop 160 is provided on the housing 36 at the “off” position andhas a detent 161 located to be engageable with the ridges. When the dialis rotated counterclockwise to the “off” position, the first ridge 150will encounter the detent 161 and the stop indicating a slow or KVOposition has been reached. Further rotation of the dial will cause thedetent 161 to pass over ridge 150 seating in the land 154 in a positive“off.” The dial material will deflect slightly. This feature alsoprevents continued rotation of the dial to prevent it from beingremoved. Rotation in the opposite direction will cause the detent toabut the ridge 152 in the full open position.

[0053] The user is provided tactile input as the dial is rotated toenhance and refine the adjustment procedure. The inner surface of theperipheral dial flange is provided with spaced grooves 164. The stop 160carries a V-shaped projection 166 which engages the grooves when thedial is assembled. The engagement is a light, frictional engagement sothat as the dial is rotated, the user will sense the “click” as theprojection 166 rides over the dial surface seating in each groove. Theengagement will also assist in preventing inadvertent rotation of thedial caused by incidental contact.

[0054]FIG. 8 illustrates another feature which provides a safety lock toprevent inadvertent movement of the dial. A deflectable lever 170extends upwardly from the middle housing 28 having an upper end with adetent 172 engageable in grooves 164 to prevent dial rotation. Thefrictional engagement, which is greater than the engagement betweenprojection 166 and grooves 164, will serve to maintain a dial settingeven if the dial is attempted to be rotated. The medical attendant mustapply an inward force to the lever 170 while holding the regulator bodyto disengage the detent 172 from the groove in which it is seated. Thedial setting can then be changed using the other hand. Release of thepressure applied to the lever 170 will cause it to return to a positionengaging the inner grooves 164 on the dial and again locking the dial inthe set position.

Operation

[0055] In the operation of the flow regulator, a roller or slide clamp,if used, is placed in a closed position and the flow regulator is placedin the tubing line at a convenient location between the drip chamber andthe administration needle, as seen in FIG. 1. The flow regulator needsto be positioned below the fluid level of the container as the device isgravity-driven. Conventional connectors and adaptors are conventionallyused and are employed to make the connection.

[0056] Air is purged from the system by opening the flow regulator tothe full open or purge position as indicated by the indicia on thecontrol dial 140 and disengaging the roller clamp/slide clamp. Once theair is purged from the system, the control knob is rotated to a positionto a fully closed position by turning on the knob to force the diskdownwardly. Once a needle is inserted in the venipuncture site “V” thecontrol dial can be rotated to the suitable selected position indicatedon the dial to establish a desired flow rate. In some instances it maybe desirable to check or confirm the flow rate by timing the drop ratethrough the drip chamber. The medical clinician will confirm the flowrate by timing the drop rate through the drip chamber.

[0057] Once the device is set at the desired flow rate, the controlmembrane 80 will function and maintain an essentially constant flow rateregardless of changes in fluid level within the IV container or patientmovement. As indicated, flow will pass from the inlet across the middlehousing to the rate control orifice 50. The position of the screw 110will determine the position of the elastomeric disk 120 relative to theorifice 50 and the radial passageway 58 of the middle housing 28controlling the rate of flow passing passing through the aperture andradially to the passageway in the membrane. Fluid will then passdownwardly and radially through the passageway in the upper surface ofthe lower outlet housing and will enter the orifice at the upper end ofthe outlet. The opening or space between the orifice and lower surfaceof the flexible membrane will vary in response to pressure in thechambers or either side of the thin membrane. It will be appreciatedthat the upper surface of the flexible membrane is subjected essentiallyto the pressure existing in the inlet. The pressure existing at theunderside of the membrane at the outlet orifice is the pressure existingat the venipuncture site.

[0058] If the pressure within the inlet chamber is reduced due to adecrease in head pressure or patient movement towards the fluid sourcethe resulting reduction in inlet pressure relative to outlet pressurewill force the membrane away from surface 76 of the land to effectivelyincrease the orifice opening to the outlet passageway with acompensating increase in flow. Conversely, by increasing the elevationof the IV fluid container, head pressure will increase and similarlyhave an opposite effect by forcing the elastomeric membrane down on itslanding and closer to the outlet port, decreasing the effective orificeopening of the outlet passageway with a compensating decrease in flow.

Calibration

[0059] Calibration is accomplished by connecting the inlet to a sourceof static fluid pressure (air or liquid). The dial has not beenassembled and the screw 110 is used to turn the regulator to an “off”position. The regulator is tested for leakage by observation and bypressure readings on a pressure gauge. Calibration is generallyperformed with reference to a head height of 32″ which is representativeof most IV set-ups.

[0060] After leak testing, the dial 140 may be affixed to the adjustingscrew by aligning the proper dial indicia “off” with the “off” positionof the screw. The dial is then rotated to the full open position so thatthe disk is not subject to pressure from the screw tip 132 that maydeform it. The unit may be packaged and subject to sterilization by gasor gamma ray as is conventional.

[0061] It will be obvious to those skilled in the art to make variouschanges, alterations and modifications to the invention describedherein. To the extent these various changes, alterations andmodifications do not depart from the spirit and scope of the appendedclaims, they are intended to be encompassed therein.

I claim:
 1. A regulator for administering an IV solution to a patientconnectable in a fluid elivery tubing line, said regulator comprising:(a) a body having a lower, intermediate and upper section; (b) a firstcontrol chamber defined between said upper and intermediate bodysections; (c) an outlet chamber defined between said intermediate andlower body sections, said outlet having an outlet port with a land areaextending about the port; (d) an inlet communicating with said controlchamber; (e) a flow passage extending from said control chamber to saidoutlet chamber having an orifice; (f) a flexible control member disposedover said orifice having adjustment means; (g) an annular flangeextending about said outlet port; and (h) a flexible membrane extendingacross said outlet chamber which membrane will oscillate in response tothe differential pressure existing between the venous pressure and fluidpressure to substantially maintain a constant set IV flow rate.
 2. An IVrate flow regulator comprising: (a) a housing having an inlet and anoutlet, said inlet connectable to a source of IV fluid and an outletconnectable to administration means; (b) said housing defining ametering port having an outlet; (c) a flexible valving member extendingacross said metering port; (d) control means cooperable with saidflexible valving member due to establish a predetermined rate of flowthrough said metering port, said control means including a manuallyrotatable control dial; (e) said housing outlet port having a landextending around said outlet port communicating with the outlet; and (f)a flexible member disposed across said land responsive to pressure headvariations to control the rate of fluid flow across the orifice and tothe outlet to substantially maintain said predetermined flow rate. 3.The IV rate flow regulator of claim 1 wherein said inlet comprises aconnector disposed at an angle with respect to the said body.
 4. The IVrate flow regulator device of claim 1 including detent means engageablein an “off” position, KYO position and full flow position to restrictmovement of said adjustment means.
 5. The IV rate flow regulator ofclaim 2 wherein said control dial has peripheral notches which cooperatewith a detent on the body to provide a tactile feed back to the user asthe dial is rotated.
 6. The IV rate flow regulator of claim 2 whereinsaid flexible member has an annular rim and a thinner control sectionextending across the area defined by said annular rim.
 7. The IV rateflow regulator of claim 6 wherein said control section has a thicknessof approximately between 0.0125″ to 0.0175″.
 8. The IV rate flowcontroller of claim 2 wherein said flexible valuing member is a siliconedisk fabricated by compression molding.
 9. The IV rate flow regulator ofclaim 2 wherein said body defines an attachment means for attachment toan accessory.
 10. The IV rate flow regulator of claim 7 wherein saidbody includes sealing ridges engaging the opposite sides of said annularrim of said membrane.
 11. The IV rate flow regulator of claim 2 whereinsaid body comprises a separate inlet, intermediate and outlet housingsections joined together.
 12. An IV rate flow regulator comprising: (a)a housing having an inlet and an outlet, said outlet extending axiallyfrom said housing and said inlet disposed and an angle with respect tothe body; (b) said housing defining a metering port having an outlet.(c) a flexible valving member extending across said metering port; (d)screw means cooperable with said flexible valving means, advanceable andretractable to establish a predetermined rate of flow through saidmetering port; (e) a manually rotatable dial on said screw means; (f)said housing outlet having a land extending around said outlet portdefining an opening into said outlet; and (g) a flexible control memberhaving an annulus and a thinner control section, said thinner controlsection disposed across said land to control the rate of fluid flowacross the orifice to the outlet to substantially maintain saidpredetermined flow rate as head height varies.
 13. The IV rate flowregulator of claim 11 wherein said body is plastic and said valvingmember and said control member are liquid injected molded silicone. 14.The IV rate flow regulator of claim 12 wherein said thinner controlsection has a thickness of approximately 0.0155″.
 15. The IV rate flowregulator of claim 11 wherein said body has sealing ridges engageablewith the annulus of the control member.
 16. The IV rate flow regulatorof claim 11 wherein a surface of the dial carries flow rate indicia. 17.The IV rate flow regulator of claim 11 wherein the screw has a pitch ofabout
 48. 18. The IV rate flow regulator of claim 12 wherein saidcontrol member has a diameter hardness of about
 55. 19. The IV rate flowregulator of claim 11 wherein the screw means has left-handed threads.20. The IV flow rate regulator of claim 15 wherein said inlet carries areference marker cooperable with said indicia.
 21. The IV flow rateregulator of claim 11 wherein said dial has a diameter greater than saidhousing.